Electrostatic flocking equipment

ABSTRACT

An electrostatic flocking equipment comprising a dosing system for flocks to be applied to a product, electrodes laterally disposed between the dosing system and the product, and means for applying an electrostatic charge to the flocks so as to accelerate them toward the product, the electrodes defining therebetween a substantially central flocking zone which is at least partly substantially free from the electrostatic charge, so as to eliminate chain and streak formation of the flocks, and thereby improve the quality of the flocked product.

United States Patent 1 1 Wirth 1 Oct. 15,1974

ELECTROSTATIC FLOCKING EQUIPMENT Arno H. Wirth, Am Heilbrunnen 67-75, 741 Reutlingen, Germany Filed: Dec. 27, 1972 Appl. No.: 318,850

Inventor:

[30] Foreign Application Priority Data Dec. 29, 1971 Germany 2165387 US. Cl. 317/3, 118/636 Int. Cl B05b 5/02 Field of Search 317/3; 118/621, 624, 625,

[56] References Cited UNITED STATES PATENTS 11/1968 Walsh et a1. 317/3 X 1/1972 Taylor et a1. 317/3 X 3,680,779 8/1972 Reilly 317/3 X Primary E.raminer]. D. Miller Assistant Examiner-Harry E. Moose, Jr.

Attorney, Agent, or Firm--Tab T. Thein [57] ABSTRACT 9 Claims 2 Drawing Figures POWER 5 SOURCE 1 ELECTROSTATIC FLOCKING EQUIPMENT The invention relates to an electrostatic flocking equipment having a dosing system for flocks to be applied to a product, below or above which, in the direction of flocking, a flocking zone is formed, and having an appropriate electrode arrangement.

In known flocking equipment with which a continuous run of a product can be continually flocked by electrostatic means, the problem presents itself that one has to prevent chain formation of the flocks as they leave the dosing system. Such a chain formation resides in that the flocks tend to form dipoles which line up or form chains on account of their electrostatic charge. This leads to streak formation on the finished product.

To eliminate such chain and streak formations, a flocking equipment became known in which an additional wire screen has been incorporated to which an electric potential is applied and which is continually cleaned by cylindrical brushes of the dosing system (hence the conventional designation brush screen).

In another embodiment of similar equipment that became known, an intermediate screen, at an electric potential, is kept free of streaks by mechanical shaking or vibratory motion, considering however that in this arrangement the streak formation is not prevented directly at the dosing system.

In both instances it is hardly possible to obtain a streak-free and satisfactory operation, and even this only when matched under optimum conditions to a particular kind of flocks. In practice this matching is usually left to chance. Besides, wear is encountered on the brush screen, while in the other arrangement the shaking device is relatively expensive and rather involved, as well as cumbersome in its technical arrangement.

It should be noted that in a known arrangement the dosing system itself forms a counterelectrode to the product run while in another equipment the potential screen is disposed between the dosing system and the product run. In both cases dosing is not free from an electrostatic field, that is it does not occur without electrically charging the flocks at the moment when they enter the flocking zone of the equipment. It is exactly this circumstance which leads to streak formation which, as mentioned before, could not be satisfactorily and completely removed in known arrangements.

It is therefore the object of the present invention to provide an electrostatic flocking equipment having a dosing system for the flocks in which it is possible to eliminate the formation of streaks with a structurally less complicated and costly arrangement. As has been mentioned in the introduction, the stray field is introduced into the substantially field-free flocking zone, depending on the particular arrangement of the main electrodes. This can be exploited for further controlling or bundling the stream of flocks emerging from the dosing system.

According to one of the important features of the invention this is accomplished in that the electrodes of the inventive electrostatic flocking equipment are disposed laterally of the flocking zone in such a manner that the zone is at least partly substantially free from electric fields.

In accordance with the invention the flocks consequently leave the dosing system and reach the flocking zone which is kept at least partly substantially free from rangement of the main electrodes. In a preferred particular arrangement according to the invention, this can be exploited for further controlling or bundling the stream of flocks emerging from the dosing system. Between the latter and the main electrodes, which produce the field, grounded control electrodes are provided for this purpose.

The product to be flocked is usually a continuous run guided below or above the dosing system. With a view to obtaining uniform flocking of such a product run, it is preferred to provide the main electrodes in the form of dishes, with their convex sides facing the product being flocked. This expedient allows a highly uniform density of the lines of force or flux to be obtained over the entire surface or width of the product run.

In a preferred, specific embodiment the main electrodes are disposed between the dosing system and the product run.

Another embodiment according to the invention is characterized in that the product run is disposed above the dosing system and the main electrodes. Herein the flocks are being brought, against the action of gravity, into the region of the force lines which accelerate the flocks toward the product run, for example by air streams and the like expedients. In this embodiment again the convex sides of the main electrodes are turned toward the product run.

The invention achieves highly uniform flocking by disposing the main electrodes, and preferably also the control electrodes, if provided, symmetrically on both sides, below or above the dosing system.

Other objects and many of the attendant advantages of the invention will be readily appreciated as the same becomes better understood by reference to the following detailed description, when considered with the accompanying drawing, wherein FIG. 1 shows schematically a first, preferred, exemplary embodiment of an electrostatic flocking equipment according to the invention, wherein the product run is below the electrodes; and

FIG. 2 shows in a similar schematic illustration a second exemplary embodiment, wherein the product run is above the electrodes.

FIG. 1 is a schematic illustration of a preferred exemplary embodiment of an electrostatic flocking equipment according to the invention, showing a dosing system 1 for flocks to be applied to a product 5, preferably passed through the equipment in a continuous run, the product being electrically grounded, and the dosing system essentially consisting of a supply bin with a perforated bottom and/or dosing brushes 7 therein.

In the exemplary embodiment, the bottom of the bin is formed by a plurality of the brushes, arranged adjacently so that their peripheries touch one another, and they are driven so as to dispense the flocks from dosing system 1.

Therebelow, a flocking zone 2 is constituted, preferably laterally limited by several control electrodes 3 which are grounded and may be punctiform, as shown. Below these electrodes, main electrodes 4 are disposed to which high potential is applied from a conventional surce (not illustrated) to produce the required electrostatic charge which accelerates the flocks from system 1 to product 5. Among the electrodes and the product run to be flocked, an electrostatic field is thus formed with force lines schematically shown at 6 (also between the electrodes 3 and 4).

On account of the field, the flocks are electrostatically attracted by the product run, grounded as mentioned before, so that the flocks are accelerated in their passage from dosing system 1 toward product 5, into which they are shot, as it were, and where they may be subsequently secured by an optional adhesive applying step and the like.

It will be seen that gravity of the flocks, small as it may be, plays a certain role in the arrangement of FIG. 1 where the flocks are accelerated within flocking zone 2 during their dropping from system 1 toward product 5. It should be understood that throughout this application, "product is understood to present individual pieces or products, continuous runs and the like, without regard to shape, length, configuration, etc. of that product."

The alternative or second exemplary embodiment of FIG. 2 constitutes a mirror image in that the flocks are released from a schematically shown dosing system la (shown here as a perforated wall and the like through which the flocks can emerge), at the bottom of the equipment, to be accelerated in upward direction, against the force of gravity, toward product run 5.

It should be understood that the dosing arrangements 1 and la are interchangeable, and neither of the illustrated arrangements should be construed as being operable only with the downward or upward flock accelerating system illustrated herein.

Numerals 3 and 4 again designate the respective control and main electrodes, the former being grounded (not shown in FIG. 2). It is important that in both embodiments the dosing space and flocking zone 2 are kept field-free. The field consequently opens into or touches laterally the flocking area where it displays high field intensity on account of the forced course of the electrostatic field, as shown by field lines 6. It should be understood that various lines have been applied to FIGS. 1 and 2, respectively, although the conditions are similar during operation of the two exemplary embodiments.

The flocks reach the. field in almost completely uncharged condition. The stray field in a direction toward dosing systems 1, la is altered by means of control electrodes 3 which are grounded, and kept away by dosing brushes 7 (in the first embodiment).

The uncharged flocks avoid the concentrated stray field at this point so that the fields in the two exeomplary equipment embodiments can be exploited for controlling the streams of the flocks. The latter subsequently hit the product runs in substantially perpendicular directions, be it either in downward or in upward direction, according to the arrangements of FIGS. 1 and 2, as explained.

Supplemental devices for the elimination or prevention of streak formation can be dispensed with in the inventive equipment. Brushes 7 of dosing system 1 remain field-free. Charged flocks do not accumulate any more at this point, as was customary with hitherto used arrangements.

It can be seen from the described and illustrated arrangements that electrodes 4, positioned laterally with respect to flocking zone 2, are so disposed that the zone is at least partly substantially free from electrostatic fields. Preferably the same arrangement applies to optional control electrodes 3. It will be appreciated that the arrangement of the lines of force is the essential novel feature of this invention. The main electrodes are arranged at a relatively short distance from the product, as compared to that from the dosing system.

In accordance with a particular, specific arrangement according to the invention, main electrodes 4 may be dish-shaped, as shown, or in the form of shells, having their convex sides directed toward product 5 and away from closing systems 1, la. During various experiments and actual production runs it has been established that the advantages of the invention are best achieved with these dish-shaped electrodes 4, as illustrated.

Preferably the arrangement is symmetrical, pairs of electrodes 3, 4 flanking flocking zone 2, as illustrated.

Electrodes 4 are preferably intermediate dosing systems 1, 1a and product runs 5.

The embodiment of FIG. 2 may be supplemented by means, such as a blower and the like producing an upwardly directed air stream, for forcibly conveying the flocks from the dosing system la at leastinto the flocking zone.

The basic inventive concept of a field-free central flocking zone is independent of the direction in which the flocks are made to impinge on the product being flocked.

It should be understood, of course, that the foregoing disclosure relates only to prefered embodiments of the invention and that it is intended to cover all changes and modifications of the examples described which do not constitute departures from the spirit and scope of the invention.

What I claim is:

1. An electrostatic flocking equipment comprising, in combination: a dosing system for dispensing flocks; an electrode system disposed between said dosing system and a product to be flocked, said electrode system being laterally disposed with respect to a substantially central flocking zone through which the flocks pass. and including at least one pair of main electrodes to which a potential is being applied, and at least one pair of grounded control electrodes; means for applying an electrostatic charge to the flocks dispensed from said dosing system, thereby to accelerate them toward the product which is grounded; and means behind the flocking zone, when viewed in the direction of flocking from said dosing system toward the product, for introducing a stray field into the flocking zone, and for bundling the flocks as they pass from said dosing system to the product; wherein the distance between said main electrodes and the product is smaller than that between the same electrodes and said dosing system; the flocking zone being kept substantially free from the electrostatic charge, thereby avoiding chain and streak formations on the finished flocked product.

2. The equipment as defined in claim 1, wherein said electrodes are symmetrically arranged with respect to said dosing system at substantially equal distances from said flocking zone.

3. The equipment as defined in claim 1, wherein said main electrodes are substantially dish-shaped, with their convex sides facing the product and turned away from said dosing system.

4. The equipment as defined in claim 1, wherein said control electrodes are substantially punctiform and spaced apart by at least the distance between said main electrodes.

5. The equipment as defined in claim 1, wherein said dosing system includes a supply bin for the flocks, with at least two rotatable dosing brushes in the bottom of said bin, for releasing a controlled amount of the flocks.

6. The equipment as defined in claim 1, wherein said dosing system is above said electrode system and the product to be flocked, allowing the flocks to reach said flocking zone by gravity.

7. The equipment as defined in claim 1, wherein said dosing sytem includes a perforated wall through which the flocks can emerge so as to reach said flocking zone.

said dosing system at least into said flocking zone. 

1. An electrostatic flocking equipment comprising, in combination: a dosing system for dispensing flocks; an electrode system disposed between said dosing system and a product to be flocked, said electrode system being laterally disposed with respect to a substantially central flocking zone through which the flocks pass, and including at least one pair of main electrodes to which a potential is being applied, and at least one pair of grounded control electrodes; means for applying an electrostatic charge to the flocks dispensed from said dosing system, thereby to accelerate them toward the product which is grounded; and means behind the flocking zone, when viewed in the direction of flocking from said dosing system toward the product, for introducing a stray field into the flocking zone, and for bundling the flocks as they pass from said dosing system to the product; wherein the distance between said main electrodes and the product is smaller than that between the same electrodes and said dosing system; the flocking zone being kept substantially free from the electrostatic charge, thereby avoiding chain and streak formations on the finished flocked product.
 2. The equipment as defined in claim 1, wherein said electrodes are symmetrically arranged with respect to said dosing system at substantially equal distances from said flocking zone.
 3. The equipment as defined in claim 1, wherein said main electrodes are substantially dish-shaped, with their convex sides facing the product and turned away from said dosing system.
 4. The equipment as defined in claim 1, wherein said control electrodes are substantially punctiform and spaced apart by at least the distance between said main electrodes.
 5. The equipment as defined in claim 1, wherein said dosing system includes a supply bin for the flocks, with at least two rotatable dosing brushes in the bottom of said bin, for releasing a controlled amount of the flocks.
 6. The equipment as defined in claim 1, wherein said dosing system is above said electrode system and the product to be flocked, allowing the flocks to reach said flocking zone by gravity.
 7. The equipment as defined in claim 1, wherein said dosing sytem includes a perforated wall through which the flocks can emerge so as to reach said flocking zone.
 8. The equipment as defined in claim 1, wherein said dosing system is below said electrode system and the product to be flocked, the electrostatic charge accelerating the flocks toward the product in upward direction.
 9. The equipment as defined in claim 8, further comprising means for forcibly conveying the flocks from said dosing system at least into said flocking zone. 